Bill Fitzmaurice

[quote name='fleabag' timestamp='1405945301' post='2506748'] Even if you use 5 or 6 string bass ? [/quote]The f3 of a Fridge is 58Hz, it doesn't seem to bother most five and six string players.

[quote name='LukeFRC' timestamp='1405894438' post='2506329']I notice the preamp has a switch on giving me a 12dB high pass filter at 80Hz. And it sounded ok! It made me think about how our rig can/ or can't produce the low end.... and the effect it has. [/quote]That filter compensates for the difference in response between an electric bass cab and a PA with subs. 80Hz is a bit high, 60Hz would be better. When you go to a concert with big PA and bass that's all boom and rumble with no definition, or for that matter even pitch, it's because the soundman has no clue what electric bass is supposed to sound like, nor how to use his PA kit to get it. By the same token one shouldn't go after an electric bass rig with flat response to 30Hz. If you get it you'll probably regret it.

It depends on the amp. Many, most notably Fender, employ a closed circuit switched output jack that shorts the output transformer when no speaker is plugged in. That would be death for a SS amp, but prevents damage to a tube amp with no load. Not having a load won't bother a tube amp at idle, only when it's being played through. [quote]My mates mesa boogie 400+ was left on standby for 15 mins with no speaker connected. The amp is now f****d.[/quote]When on standby only the heater voltage is active, the B+ voltage is not, so even if being played through no damage is possible. I haven't seen Mesa schematics but being basically upgraded Fenders I very much doubt that they don't use switched output jacks.

[quote name='GrammeFriday' timestamp='1404643449' post='2494333'] but he was using an all-TC rig last time I saw him (playing with Supersilent) and the sound was amazing. [/quote]You mean the sound of the PA was amazing. You probably couldn't hear a note from the backline.

[quote name='Painy' timestamp='1404601722' post='2494143'] Good to know thanks. Oh, and Mrs Painy says thanks too - seeing as I won't need to spend the money on a replacement speaker now, she says I can use it towards a present for her birthday next week! [/quote]Manolo. Trust me.

[quote name='Painy' timestamp='1404597555' post='2494108'] would there be any risk of damage to either the amp or cab in continuing to run it as is? [/quote]No. If anything the higher total impedance load will let your amp run cooler.

Don't worry about not getting the full 500 watts out of it. You can't hear watts. You do hear decibels.The difference between running a 4 ohm versus 8 ohm extension cab might be at best 2 decibels, which is roughly the difference between running your volume control at 7 versus 6.75. It's simply not worth changing the driver, the advantage being so slight. You also do not want to run a 4 ohm 4x10. If you do each ten in the combo will receive twice the power as each ten in the extension. Probably the best extension option would be a 4 ohm 2x10 loaded with the same drivers as those in the combo.

[quote name='bassmachine2112' timestamp='1404329127' post='2491684'] I don,t know the physics side [/quote]I do. They sound exactly the same as one of the same drivers, the Eminence Deltalite II 2512, will sound in a cabinet of twice the net internal volume with the same tuning. After accounting for the space taken up by the second driver and the space in between them the actual size savings is perhaps 40%. But most manufacturers don't load drivers into a cab as large as they should, because that's not what most customers want. Speaker design always boils down to compromise. If you have more money than pack space an SP may make sense for you. If you have more pack space than money a correctly sized cab may be the better option. The trick lies in finding a correctly sized cab, as very few are.

If you run them together each cab will receive the same power. That means each driver in the 2x10 will get twice that which those in the 4x10 do. For a correct match the impedance of the 2x10 should be twice that of the 4x10.

[quote name='LukeFRC' timestamp='1403976887' post='2488296'] At which point I don't know why they bother giving those figures. It's so so different to the PA world where everything is spelled out. [/quote]Bass players get gigs by being competent playing their instruments. That doesn't require a high level of technical knowledge.PA guys get gigs by being competent producing good sound. That requires a high level of technical knowledge. I'm generalizing of course, not all working PA techs are competent by any means. I'm in Montreal for the jazz festival. Last night I saw concerts at five outdoor venues, only one sounded good. Not concidentally it was at the largest/most important venue. It's a very safe bet the crew there got the gig by having a reputation for knowing what they're doing. It's also a very safe bet they got paid a lot more than the hacks at the other venues. Knowledge may be its own reward, but it carries a lot of other perks as well.

Headroom is mainly defined by the capacity of the power supply. Wattage ratings have skyrocketed, but the actual capacity of the power supplies has not.

[quote name='LukeFRC' timestamp='1403952681' post='2487973'] It all depends at what point they are measuring the frequency point from! -3dB, -6dB or -10dB - without that information the frequency response info isn't really that useful.[/quote]They're probably -20dB. Those numbers are utterly silly where electric bass speakers are concerned. They simply don't go that low, by about an octave. [quote]I would google around for Bill Fitzmaurice's advice on mixing speaker sizes.... and make your choice from that. [/quote]In a word, don't.

No witchcraft, just simple physics. Two drivers coupled allows the cab size to be smaller. But there's no such thing as a free lunch with physics. The price paid for the smaller cab is that the output is the same as with only one driver in a larger cab. IMO a 2x12 that only goes as loud as a 1x12 isn't worth the slight net savings in size compared to a standard 1x12.

[quote name='Ben Jamin' timestamp='1403476933' post='2483147'] I'm thinking it be much more efficient to split my signal and send the subs to the SWR and the rest to the Compact, [/quote]Probably not. I doubt that the Big Ben goes much lower, if at all, than the compact, and doing this might end up giving you less low end.

[quote name='fleabag' timestamp='1403103896' post='2479811'] Its hard to imagine why the Beymas are cheaper than Betas. [/quote]In the US the Beymas are $130, the Betas are $80. The US price for the Deltalite II 2510 is $140.

[quote name='MoonBassAlpha' timestamp='1402923497' post='2477892'] A sealed cab of appropriate dimensions will give a gentle bass roll-off, yes?[/quote]Yes, and no. The roll off is lower slope but the f3 is much higher, so you don't get better low end, you get less. On average a sealed cab only works better than ported below 30Hz, which is of no benefit for electric bass.

[quote name='MoonBassAlpha' timestamp='1402919831' post='2477834'] Speaker is Celestion bn200x, Thinking of making the cab taller than the previous trapezoid shape. I seem to remember the volume needed to be about 1 square foot, is this right? or different for sealed?[/quote]Have you modeled the driver using speaker modeling software to determine required cab volume, and to compare both response and maximum SPL of sealed versus ported? That is the first step in designing a cab.

[quote name='chriswareham' timestamp='1402850442' post='2477229'] in the case of the Vox Foundation they allegedly made the cabinets to the size they wanted (to match the AC50 head) and just bunged in a speaker without concerning themselves whether it was an ideal match. [/quote]In 1965 they had no way of knowing. Use of Theile/Small parameters was in its infancy, and was not widely known until a decade later. A modern 1x18 is about twice that net volume, and is properly ported.

Google 'schematic' for the amp, chances are it's out there.

Tilt the cab back, so that it aims at your head. You'll be able to hear yourself much better that way. If it's still not enough you need to investigate a better speaker, your head has plenty of power.

[quote name='discreet' timestamp='1402316668' post='2471988'] No, I believe Chris Squire and others did it years ago. I think he used two Fender Twin Reverbs at one point. Edit: This from his website: 'Chris’s rig…Marshall 100 watt head with a Marshall 4 x 12 speaker cabinet, two Ampeg SVT-2 Pro heads, two SVT- 8 x10 speaker cabinets, an SWR amplifier head for the Bass Pedals, and an SWR 2 x 15 speaker cabinet. Effects wise – a Samson stereo radio and receiver, a Sound Sculpture, which is a switching matrix to blend the effects together, a spare one, a Hush Unit, then the effects which are a Maestro Fuzz Unit, a custom built tremolo, an TC Electronics Chorus. On the bottom shelf we have a TC Reverb, a TC Delay, and a Mutron pedal from the 70's.' [/quote]He did use a Twin in the studio for the distortion on the first album. If I wanted that sound today I'd run a regular bass rig plus a 1x10 or 1x12 guitar combo.

[quote name='Balcro' timestamp='1402308063' post='2471833'] I've run it's specs through winISD, the first JBL I've checked, and it's the first unit I've come across that handles more than it's rated capacity and laughs at the amp power! It handles the full 150 watts all the way down to it's fundamental resonance @ 35Hz. I think that's it's thermal limit, but at the same time it never exceeds the mechanical "xmax" until the same low point. [/quote]It's certainly better than most vintage drivers, but today the 7mm xmax is about average. The main issue with it is the low (0.25) Qts, which chokes off low frequency response. In that respect JBL made it 'too good', as were most of the D, K and E series drivers, which were designed before T/S. Only after T/S came along was it understood that, while high sensitivity was in general a good thing, it could be overdone.

[quote name='davidlovellbass' timestamp='1402226374' post='2471094'] I was hoping to swap the JBL out for an Emience basslite C2515 but spending out for a speaker that could sound bad isn't very appealing [/quote]You need to go to the JBL Professional site and download their T/S spec sheet, then find a driver with similar specs to the E145. However, that only shows the low frequency compatibility, up to about 200Hz, not the midrange. You'd need to compare that on individual driver data sheets. The kicker though is that doing this only gets you something that's similar to the E145, it doesn't mean it's a perfect match to the Karlson, which the JBL may or may not be. Kep in mind that the Karlson dates to circa 1950, the E145 to circa 1970, so the Karlson was not designed using the E145 as a test driver.

[quote name='davidlovellbass' timestamp='1402165233' post='2470694'] Anyone have any ideas for a replacement speaker that isn't so heavy? [/quote]There are many, the problem is matching anything to a Karlson box. It's a seat of the pants design that can't really be software modeled to get a good driver match.

Do a thread search about driver replacement and you'll find reference after reference that you can't just plop a driver into a cab and get a good result. They must be matched. As for not seeing bass dedicated eighteens, that's because with the driver technology that's existed for the last 15 years or so you can now find tens that have higher output and lower response than vintage eighteens, while eighteens have poor highs and virtually no dispersion in the mids. In short, we no longer use eighteens because we don't have to. Chances are your cab is undersized for an eighteeen anyway, and would work better loaded with a twelve or fifteen. Exact internal dimensions would be required to determine what would work best. The driver you linked to is, frankly, a POS. Don't even think about using that.